Dead Zones in LX‐17 and PBX 9502

Abstract

Pin and X‐ray corner turning data have been taken on ambient LX‐17 and PBX 9052, and the results are listed in tables as an aid to future modeling. The results have been modeled at 4 zones/mm with a reactive flow approach that varies the burn rate as a function of pressure. A single rate format is used to simulate failure and detonation in different pressure regimes. A pressure cut‐off must also be reached to initiate the burn. Corner turning and failure are modeled using an intermediate pressure rate region, and detonation occurs at high pressure. The TATB booster is also modeled using reactive flow, and X‐ray tomography is used to partition the ram‐pressed hemisphere into five different density regions. The model reasonably fits the bare corner turning experiment but predicts a smaller dead zone with steel confinement, in contradiction with experiment. The same model also calculates the confined and unconfined cylinder detonation velocities and predicts the failure of the unconfined cylinder at 3.75 mm radius. The PBX 9502 shows a smaller dead zone than LX‐17. An old experiment that showed a large apparent dead zone in Composition B was repeated with X‐ray transmission and no dead zone was seen. This confirms the idea that a variable burn rate is the key to modeling. The model also produces initiation delays, which are shorter than those found in time‐to‐detonation.

High‐Resolution Numerical Simulation of Detonation Propagation and Dead Zones in LX‐17

“…The geometry of LX‐17 double‐cylinder calculation is shown schematically in Figure 8, which is cylindrically symmetric around the heavy line. The calculation geometry is a repeat of experiments performed by Ferm [1] and Souers et al [34]. The booster is a bare charge cylinder with a radius of 6 mm and a length of 30 mm, which is ignited at the point A on the symmetry axis.…”

Desensitization by Pre-shocking in Heterogeneous Explosives and its Numerical Modelling

“…A single reaction rate equation was used, which was a stripped down version of the Lee-Tarver ignition and growth model, and the coefficients of this rate equation were different in different regions of the explosive. In a more recent approach, Souers et al [30] later refined his model by employing a single reaction rate format, which varied for different pressure regimes in the explosive to simultaneously model dead zone, failure region and the detonation region in corner turning experiments. This model could reproduce various experimental features, including the detonation failure region in the corner turning experiments of LX-17.…”

Shock-to-Detonation Transition simulations

“…This is relevant to detonator/booster applications, and to some accident scenarios involving a projectile impacting an HE. Several types of experiments provide data on this phenomena; such as the mushroom test [Hill et al, 1997], hockey puck test [Souers et al, 2006] and onionskin/furball test [Francois et al, 2014].…”